As a prior art throttle sensor, there has been proposed one wherein, as disclosed in Japanese Utility Model Publication No. 99109/1982 published on June 18, 1982 entitled "Throttle open degree detector", a sensor element is of the stand-alone type, and the sensor element including a bearing is mounted on a throttle body, thereby to detect the rotational angle of a throttle valve spindle.
The prior art throttle sensor has been structurally such that, since the sensor element and the throttle body are separated each other, the former has the bearing portion, a joint etc. Therefore, the structure of the sensor element has become complicated causing such problems as a large size and a high cost.